Fix source position for stack traces with optimized top function.

runtime/vm/flow_graph_compiler.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_XXX.
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/cha.h"
 #include "vm/dart_entry.h"
@@ skipping 134 matching lines @@
       stackmap_table_builder_(
           is_optimizing ? new StackmapTableBuilder() : NULL),
       block_info_(block_order_.length()),
       deopt_infos_(),
       static_calls_target_table_(GrowableObjectArray::ZoneHandle(
           GrowableObjectArray::New())),
       is_optimizing_(is_optimizing),
       may_reoptimize_(false),
       double_class_(Class::ZoneHandle(
           Isolate::Current()->object_store()->double_class())),
-      parallel_move_resolver_(this) {
+      parallel_move_resolver_(this),
+      pending_deoptimization_env_(NULL) {
   ASSERT(assembler != NULL);
 }
 
 
 bool FlowGraphCompiler::HasFinally() const {
   return parsed_function().function().has_finally();
 }
 
 
 void FlowGraphCompiler::InitCompiler() {
@@ skipping 51 matching lines @@
     entry->PrepareEntry(this);
     // Compile all successors until an exit, branch, or a block entry.
     for (ForwardInstructionIterator it(entry); !it.Done(); it.Advance()) {
       Instruction* instr = it.Current();
       if (FLAG_code_comments) EmitComment(instr);
       if (instr->IsParallelMove()) {
         parallel_move_resolver_.EmitNativeCode(instr->AsParallelMove());
       } else {
         ASSERT(instr->locs() != NULL);
         EmitInstructionPrologue(instr);
+        ASSERT(pending_deoptimization_env_ == NULL);
         pending_deoptimization_env_ = instr->env();
         instr->EmitNativeCode(this);
+        pending_deoptimization_env_ = NULL;
         EmitInstructionEpilogue(instr);
       }
     }
   }
   set_current_block(NULL);
 }
 
 
 void FlowGraphCompiler::Bailout(const char* reason) {
   const char* kFormat = "FlowGraphCompiler Bailout: %s %s.";
@@ skipping 289 matching lines @@
       // This IC call may be closure call only.
       label_address = StubCode::ClosureCallInlineCacheEntryPoint();
       ExternalLabel target_label("InlineCache", label_address);
       EmitInstanceCall(&target_label,
                        ICData::ZoneHandle(ic_data.AsUnaryClassChecks()),
                        arguments_descriptor, argument_count,
                        deopt_id, token_pos, locs);
       return;
     }
     // Emit IC call that will count and thus may need reoptimization at
-    // return instruction.
+    // function entry.
     ASSERT(!is_optimizing() || may_reoptimize());
     switch (ic_data.num_args_tested()) {
       case 1:
         label_address = StubCode::OneArgOptimizedCheckInlineCacheEntryPoint();
         break;
       case 2:
         label_address = StubCode::TwoArgsOptimizedCheckInlineCacheEntryPoint();
         break;
       case 3:
         label_address =
@@ skipping 441 matching lines @@
     if (i != largest_ix) {
       // Swap.
       CidTarget temp = (*sorted)[i];
       (*sorted)[i] = (*sorted)[largest_ix];
       (*sorted)[largest_ix] = temp;
     }
   }
 }
 
 }  // namespace dart